The present invention concerns compositions which are useful to counter damage caused by harmful agents, particularly anti-neoplastic agents used in cancer treatment, e.g. cytotoxic drugs. Damage in the context of the present invention means adverse effects on either cells, tissue or organs. The present invention also concerns therapeutic methods to counter such damage. Furthermore, the present invention concerns also novel compounds useful in such compositions and methods.
Most of the commonly used antineoplastic treatments, including chemotherapy and radiation, have adverse toxic effects, manifested on dividing cells and in the function of certain organs. Cells which are particularly affected by such treatment are bone marrow cells, skin cells and cells of the gastrointestinal tract epithelium. In addition, such treatments often cause damage to specific organs, such as the kidney and liver. As a result of such toxic effects, the therapeutic index of such treatments is limited.
It is a long felt want in medical research to try and develop treatment modalities and means which will reduce the unwanted toxic side effects, without affecting the therapeutic activity of the drugs, thus increasing their therapeutic index.
Apoptosis or programmed cell death is a fundamental physiological mechanism of cell death regulated during embryonal development and normal homeostasis mechanisms within the body. Recent data indicated that the anti tumor effect of a variety of chemotherapeutic agents is related to their ability to induce apoptosis. The toxicity of these agents may also be related to the induction of apoptosis in normal cells.
Preliminary reports have described use of various pharmacological agents for the prevention of nephrotoxicity resulting from the use of anti-cancer drugs (Skinner, R., Current Opinion in Oncology, 7:310-315, 1995). Attempts were made to counteract the severe chronic proximal tubular toxicity resulting from use of the cytotoxic drug Cisplatin. In in vivo experiments in rats, para-aminobenzoic acid (PABA) co-administered together with cisplatin resulted in reduced nephrotoxicity of the cisplatin without reducing its anti-tumor activity. Other agents such as mitimazole, chloropromazin and L-arginine were also administered to animals in various in vivo experiments carried out in connection with toxicity of cisplatin resulting in only preliminary non-conclusive findings.
The drug amifostine which is dephosphorylated to yield a thiol moiety was also used for reducing anti-toxic effects of anti-neoplastic drugs (Cancer Res., 55:4069, 1995).
The present invention provides, by a first of its aspects, a pharmaceutical composition for countering, i.e. reducing or preventing, damage to cells or tissue comprising, as an active agent, an effective amount of a compound of the general formula I: 
wherein:
Ar is a group of the formulae 
n is 0 or, when Ar has the formula (i) above, then n may also be 1,
R is CN, xe2x80x94C(S)NH2, xe2x80x94C(O)NHR3 or, when R1 is 4-NO2 and R2 is H or 3-OH, then R may also be a group of the formula 
xe2x80x83where R3 is H, phenyl, phenyl(lower alkyl) or pyridylmethyl;
R1 and R2 are each independently H. OH, NO2 or, when R is CN, also CH3, F, or CF3, provided that both R1 and R, are not simultaneously H, together with a pharmaceutically acceptable carrier.
Said active agent and said pharmaceutical composition may be administered to or contacted with cells or tissue in a variety of conditions to reduce or prevent undesired damage to cells, tissues or organs. Examples of such conditions are such which may lead to apoptosis. Preventing of undesired apoptosis is a specific embodiment of the invention. Such conditions may also be exposure of said cells, tissue or organ to harmful factors, which may be exogenous or endogenous factors, as well as other physiological conditions, which may lead to damage, e.g. change in temperature, impairment of blood flow, exposure an ionizing irradiation, etc. The damage to be prevented may also be a result of natural physiological deterioration processes, e.g. such occurring( in cells, tissue or organs, maintained, grown or cultured ex vivo.
The present invention also provides a method of treatment of an individual, for countering damage to cells, tissue or organ, comprising administering to the individual an effective amount of a compound having the general formula I.
The term xe2x80x9ceffective amountxe2x80x9d should be understood as meaning an amount of the active compound, which is effective in countering damage manifested in either destruction of normal (non-diseased) cells or damage to a tissue or organ.
The harmful factor may be an exogenous agent e.g., a therapeutic drug having a cytotoxic effect (e.g. anti-neoplastic drugs), irradiation, noxious chemicals, etc. In addition, the harmful factor may be endogenous, such as free radicals the level of which rises in the course of various metabolic or other disorders, auto-antibodies, cytokines, etc.
The pharmaceutical compositions of the invention may be used in the framework of treatment of various diseases, disorders or conditions such as AIDS, conditions which may give rise to hepatotoxicity, radiation injuries, reducing or inhibiting damage to grafted cells or tissue as a result of graft rejection, for the treatment of intoxications, e.g. paracetamol intoxication, for countering adverse effects of noxious solvents and carriers of therapeutic drugs, countering alcohol-caused damages, etc. Furthermore, the compositions may also be used for countering non-desired immune mediated reactions or an inflammatory response, e.g. septic shock, to reduce damage caused by autoimmune reactions and others. Finally, the pharmaceutical compositions of the invention also may be used- in ex vivo preservation of cells, tissues or organs used for transplantation to reduce or prevent cell or tissue deterioration or death which may otherwise occur during the time they are kept ex vivo prior to transplantation, etc.
The pharmaceutical compositions of the invention are especially useful to counter toxic effects of cytotoxic or anti-metabolic drugs, particularly such as used in cancer therapy. Occasionally, the pharmaceutical composition of the invention will be administered in conjunction with the cytotoxic drug. A pharmaceutical composition according to this embodiment may comprise such a drug in combination with a compound of above formula I.
The compounds of formula I belong to a family of compounds known as Tyrphostin compounds (Levitzki, A. and Gazit, A. Science, 267:1782, 1995). In the following text, a compound of Formula I will be referred to as xe2x80x9cTyrphostinxe2x80x9d and compositions comprising such compounds will at times be referred to as xe2x80x9cTyrphostin compositionsxe2x80x9d.
Out of the tyrphostins of formula I, some are known, albeit for uses other than those provided by the invention, and others are novel. The novel tyrphostins, which constitute another, independent aspect of the invention, are those of formula I, wherein Ar, R1 R2 and R3 are as defined above, with the provisos that
a) R cannot be 
b) when R is CN and n is 0, then
(ba) if one of R1 and R2 is H or OH, then the other cannot represent NO2;
(bb) if one of R1 and R2 is H or F, then the other cannot represent H or F; and
c) when R1 is 4-NO2, R2 is H and n is 0, then R cannot representxe2x80x94C(O)NH2 or xe2x80x94C(S)NH2.
Preferred compounds of formula I for use in the compositions are those wherein R is CN, xe2x80x94C(S)NH2, xe2x80x94C(O)NHCH2C6H5 or a group of the formula 
and n is 0, R1 is 4-NO2 and R2 is H.
Examples of tyrphostins are shown in compound Table I. Some of the tyrphostins shown in Compound Table I are novel, and these novel tyrphostins are shown also in Compound Table II.
1. Mowry, D. T., J. Am. Chem. Soc., 67:1050, 1945
2. Zabichy, J., J. Chem. Soc., 683, 1961.
3. Bronskill, J. S., Dc A., and Ewing, D. F., J. Chem. Soc. Perkin, Trans. I., 629, 1978
4. Junck, H., and Wolny, B., Moncat. Chem., 107:999, 1976
5. Novogrodsky A. Vanichkin, A., Patya, M., Gazit, A., Osherov, N. and Lcvitzki, A., Science, 264:1319, 1994
6. Sakamoto, M., et al., J. Chem. Soc., Perkin Trans I., 1759, 1995
7.
(a) Flenner, A. L., C. A. 63:13,278, 1965
(b) Lythgoe, K., Todd, A. and Tapham, C. J. Chem. Soc., 515, 1944
8. Drabek, J. and Meyer, A., C. A., 89 152,719, 1978
9. Gazit, A., et al., J. Med. Chem., 34:1896, 1991
10. Carson, B. B., and Staughton, R. W., J. Am. Chem. Soc., 50:2825, 1928.
11. Gazit, A., et al., J. Med. Chem., 32:2344, 1989
12. Weinberger, M. A., and Higgin, R. M., Can. J. Chem., 43:2585, 1965
13. Blox Ram, J., Dell, C. P., and Smith, C. W., Heterocycles, 38:400, 1994.
Particularly preferred tyrphostins in accordance with the invention are the compounds designated as AG1714, AG1744, AG1801 and AG1843 in the above xe2x80x9cCompound Table Ixe2x80x9d. Out of these four compounds, the latter two are novel.
The tyrphostins of formula I may be administered to the patient in combination with another treatment, c.g. in combination with a cytotoxic drug or irradiation. In such a combination treatment the tyrphostins may be administered simultaneously with or at a different time than the other treatment, so as to yield a maximum effect. A particular example is administration of the tyrphostins prior to the other treatment, e.g. several hours prior to the irradiation or to the administration of the cytotoxic drug.
It was found in accordance with the invention that when the tyrphostins of formula I are administered together with another therapeutic agent, they do not reduce the therapeutic activity of the other agent, but rather act in reducing its undesired toxic side effects to normal cells or tissue. This means that the therapy with the therapeutic agent will still achieve the same desired therapeutic effect, at the same dosage. For example, in the case of a chemotherapeutic drug, the administration of a tyrphostin will not, or may only minimally affect the effect of the drug in reducing the tumor load or preventing tumor growth or tumor recurrence, at a given administration dosage. In some cases, however, administration of the tyrphostins even intensifies the therapeutic effect of the treatment. The overall effect of the tyrphostins, in such a combination therapy, is thus the increase in the therapeutic index of another therapy, namely, increase in the ratio between the therapeutic effect of the therapy to its undesired toxic side effects. The increase in therapeutic index may at times be used to advantage of increasing the dosage of the therapeutic agent, e.g. the dosage of the cytotoxic agent or radiation, without a concurrent increase in undesired toxic side effects.
The tyrphostins according to the invention may be administered either in a single dose or may be given repetitively over a period of time, e.g. prior, during and after the treatment with a cytotoxic agent or irradiation.
A preferred mode of administration of the tyrphostins to humans is intravenously, although by a proper formulation, they may also be administered by other administration modes, c.g. intramuscularly, intraperitoneally or orally.
While the tyrphostin compositions will typically contain a single tyrphostin compound, it is possible at times to include in the composition and or co-administer two or more tyrphostins which act together in a synergistic or additive manner to counter damages caused, e.g. by a therapeutic treatment.